Small form factor devices like ultrabook computers, tablets, and smartphones accommodate as many as five to seven antennas or more to cover Wi-Fi, Bluetooth, cellular data networks such as LTE (Long Term Evolution) or 3G (Third Generation Cellular), FM (Frequency Modulation) radio, GPS (Global Positioning System), RFID (Radio Frequency Identification), NFC (Near Field Communication) and DTV (Digital Television broadcasting) services, among others. The number of antennas, their sizes and their RF isolation requirements put severe restrictions on the device's form factor and design. Traditionally discrete components have been used for both antennas and inductors which were typically placed on the motherboard. If antenna size can be significantly reduced, the overall size of the communication device can be reduced or more of the device may be used for other purposes.
As an example a typical popular tablet computer may have four antennas, a planar inverted F cellular band antenna (GSM/WCDMA/LTE) and a Wi-Fi/Bluetooth antennas among others. The cellular band antenna may measure roughly 35 mm by 10 mm and the Wifi/Bluetooth antenna may measure roughly 16 mm by 10 mm. The antennas may also have complex shapes to optimize reception that impact design freedom for the rest of the device.
Efficient RF antennas are just one example of small form factor magnetics that are suitable for future microelectronic packages used in mobile, small scale, and wireless systems. Inductors for power delivery and other components are also desired. While discrete components placed on the motherboard have been used for both antennas and inductors, this can significantly impact the size of the final product. The size of such components is physically limited by the materials and electrical specifications. While high relative permeability can allow for smaller devices, high permeability materials tend to also be conductive. This causes eddy current losses and other drawbacks.